Signaling system



Nov. 9 1926. 1,606,316

P. B. MURPHY SIGNALING SYSTEM Filed June 30. 1924 4 Sheets-Sheet 1 Nov. 9 1926. I 1,606,316

I P. B. MURPHY SIGNALING SYSTEM Filed June so. 1924 4 She ets-Sheet 2 Nov. 9 1926. 1,606,316

P. B. MURPHY SIGNALING SYSTEM Filed June 30. 1924 4 Sheets-Sheet 3 PAM-l1- Nov. 9 1926. 1,606,3lfi

P. B. MURPHY S IGNALING SYSTEM- Filed June 30. 1924 v 4 Sheets-Sheet 4 Patented Nov. Q, 1926:

PAUL B. MURPHY, OF NYAGK, NEW YORK, ASSIGNOB TO VKT'ES'JZ'ERN ELECTRIG COM- PANY, INCORPORATED, OF NEW YORK, N. Y., A. CORPORATION OF NEW YORK.

SIGNALING- v sxsrn'm'.

Application filed June so, 1924. Serial No. 723,143.

This invention relates to signaling. systems and more particularly to improved methods and means for signaling over transmlsslon. lines.

To attain these objects according to one feature of the lnvention, sources of alternat1ng current within the voice range of frequencies are employed for the signals Under the present telephone practice intransmitted over the toll lines to accomplish volving the use of telephone lines inter-connectiugdiflerent exchanges, several different methods of extending connections are employed, such as, manual to manual, manual to automatic or automatic to automatic con ncctions. In a manual to manual connection, the subscriber in the originating exchange firstsecures a connectionto a toll operators position in his own exchange, who then extends the connection over a toll line to a distant exchange and rings up the toll operator at such an exchange. The toll operator at this exchange requests of the originating toll operator, thevnumber of the desired line and then proceeds to extend the connection to the desired subscriber. In a manual to automatic connectionthe toll operator in the'originating exchange dials the desired line in the automatic exchange without the aid of the toll operator at a distant exchange and in an automatic to automatic connection, no operators are involved but the calling subscrlber merely dials the number of the wanted subscriber and the connection is completed over the toll line between the two exchanges. Connections of these types may extend through a number of manual or automatic exchanges involving the use of several toll lines.

It is the object of this invention to provide cord circuit and toll line equipments suitable for use in the extension of connections of the above types.

Another object is to provide means associated with such cord circuits and toll line equipments, whereby any one of the well known types of toll lines may be employed such as, for example, ordinary wire toll lines with or without repeaters, achannel of a carrier telephone installation, a radio telephone conn-ection, composite lines or phantom lines. That is, the nature of the signals, used for performing the various functions incidental to the extension of a connection is such that the signals may be transmitted over any toll line the same distance and at the same efilciency as the ordinary voice modulated signals and without in any Way curtailing the usefulness of these various types of toll lines.

the various switching and supervisory functions; A single frequency is used for transmission in eachdirection and means is provided at each end of the toll lines for automatically interrupting these frequencies at various rates and transmitting such signals to the receiving end to cause corresponding switching and signaling functions to be performed.

' The nature of the invention will more fully appear from the following specification read in connection with the accompanying drawings in which Fig. 1 shows the connection from a subscribers line diagrammatically with a toll operators cord circuit and associated dialing circuit arranged in accordance with this invention located at one manual exchange. By means of this equipment a 'toll operator may extend connections either to another toll operator located at another manual exchange or to a subscriber reached through an automatic or machine switching exchange. Fig. 2 represents the outgoing end of a special toll li'ne equipment arranged in accordance with the invention, located at the originating exchange, and by means of which voice frequency alternating current signals maybe transmitted to and received from the distant exchangeover any type of toll line associated therewith. Fig. 3 represents the incoming end of the special toll line equipment arranged in accordancewith this invention,'located at a distant exchange, and by means of which voice frequency alternat-' ing current signals may be received from or transmitted to the originating exchange. Fig.4 represents a portion of an automatic exchange by means of wh ch automatically called subscribers lines may be reached from the above mentioned toll line equipments.

Referring now to the drawings, trafiic over the system shown and arranged in accordance with this invention, may be outlined as follows: If it is assumed that a subscriber at 10. has established a connection as far as to the toll -operators position 100 and the toll operator has inserted the answering plug L2 of the cord circuit shown at 100 into jack'll, and. ascertained the number of the desired line, the toll operator will then in-' sert the calling plug 15 of this cord circuit into the jack 210 of the outgoin trunk line equipment 200 associated witht e toll line 220 leading to the incomin toll line equipment 300 at a distant exc ange. The toll operator at 100 then proceeds in either one of two manners to extend the connection:

If the wanted subscribers number can only be reached through the service of a toll operator such as the one at position 310 at the distant exchange, she proceeds to call this toll operator in the usual manner well known in the art except that alternating currents within the voice range interrupted at a certain rate' is used for the necessary, signal indications. That is, she causes instrumentalities in the cord circuit and the outgoing toll line equipment 200 to be operated to transmit voice frequency alternating currents of for example, 1000 cycles interruptedat a 20 cycle rate over the toll line 220 to the incoming toll line equipment 300 at the distant exchange, these signals then condition the incoming toll line equipment-300 for a manual connection and are translated by the receiving circuit equipment 350 into indications that will not only call the attention of the toll operator at position 310 to the fact that a connection is desired requiring her cooperation, but will also serve as supervisory signals during the establishment and times tablishment of such a connection as Well" as,

when the connection is established.-

Similar operations of the system take place if the toll operator at position 310 desires to call the toll operator at position 100 except that in this case instead of sending voice frequency alternating currents of 1000 cycles interrrupted at a 20 cycle rate, voice frequency alternating currents at, for example, 700 cycles interrupted at a 20 cycle rate are transmitted over the toll line 220 and translated by the receiving circuit equipment 250 at the outgoing toll line equipment 200 into signal indications for the attention of the V toll operator at position 100.

On the other hand if the wanted subscribers line is located in an automatic exchange such as the one diagrammatically disclosed in Fig. 4, the toll operator at position proceeds by the operation of a dialing key to connect the common dialing circuit equipment 150 to the cord circuitshown and by means of instrumentalities associated with this dialing circuit, the cord circuit and the outgoing toll line equipment 200, causes voice frequency alternating currents of, for example, 1000 cycles to be transmitted, in one instance interrupted at a 40 cycle rate while inanother instance, that is, in the case of the operations of the dial interrupted at the rate of dialing, the corresponding signals received at-the incoming toll line equipment 300 first prepare thisequipmentffmi the extension of an automatic connection and are translated by the receiving circuit 350 to cause the automatic exchange equipment shown in Fig. 4 to extend the connection to the wanted subscribers line as well as to cause the various supervisory signaling indications to be given during the establishment and disestablishment of the connection. I The arrangement of the toll line equlpments'are such that various signals for the supervision of the connection are transmitted back to the toll operator at position 100 during the progress of the call as well as in the breaking down of the connection. Such signals consist of the voice frequency alternating currents of 7 00 cycles interrupted at various rates such as at a 40 cycle rate or signal indications consisting of the voice frequency alternating currents of 700 cycles interrupted at the 40 cycle rate in the shape of impulses of ,60 per minute, which latter impulses are used when all of the toll lines are busy or signal indications of the voice he a v quency alternating currents of 7 00 cycles interrupted at the 40 cycle rate in the shape of impulses of 120 per minute which im-' pulses are used when the called line is busy. Such signals are all translated by the receiving circuit equipment 250 at the outgoing toll line equipment 200 into the proper supervisory signal indications for the operatorat the position 100.

It is to be understood that the various frequencies of the alternative current sources mentioned and the rates at which they are interrupted are simply illustrative and that the invention is not limited to the employment of these particular values but that any frequencies within the voice range'and rates of interruptions most suitable to particular cases in the practice of the invention, may

be selected.

It is believed that the arrangement shown.

will be more fully understood from the following detailed description of series of calls of the types that may be completed thereby. The first type of connections to be considered will he calls extendedvon the so-called ring down basis, i. e., from a subscriber 10 to a toll operators position 100 at the origis nating exchange to the toll operator attending position 310, at the distant exchange and vice versa. The circuits beyond this point,

have not been shown as they form no part of thisinvention and as it is well known and understood in the art how manual connections are attended to by outgoing as well as incoming toll operators no further explana tions will be made in this respect. Assuming then that the toll operator at 100 has insubscribers line by theconnection of his tel-- sorted plug 12 into jack 11 and the operator has ascertained the number of the wanted tact of relay 216 to ground. The operationof relay 24 forms no useful function at this time. The operation of relay 23, however, closes a circuit for relay 26 as follows: battery armature and front contact of relay 23, outer right hand armature and back contact of relay 42, winding of relay 26, armature and back contact of relay 30 to ground. It I should be noted that a circuit is also closed from the battery at relay 23 through lamp 25 and winding of relay 27 in parallel through armature and back contact of'relay 26 to a ground at a normal contact of the listening key However, this circuit is prevented from lighting the lamp 25 and operating the relay 27 as relay 27 is slow to opcrate in comparison with relay 26, so that this circuit is almost immediately broken. The operation of relay 202 closes an energizing circuit for relay 203 from battery, winding of relay 203, right hand armature and front contact of relay 202 to ground. Relay 203 in operating closes a circuit for the busy signal 205 as follows: battery and left hand armature and front contact of relay 203, winding of busy signal 205 to ground operating this signal to indicate to other toll operators that the toll line 220 connected. to this equipment is busy. She then proceeds to ring the toll operator at the distant ex-" change by operating ringing key 34. This causes a 20 cycle alternating current source to be connected to the ring lead and ground to the tip lead of the cord circuit and the outgoing toll line equipment in which a bridged circuit containing retardation coils 206, a condenser 207 and an alternating current relay 208 are located. Relay 208 responds to the 20 cycle current and in operating closes a circuit as follows: battery, winding of relay 209, armature and front contact of relay 208 to ground. Relay 209 operates and disconnects the outgoing end of the line from the tip and ring leads to the jack 210 and connects the outgoing end to a source of 1,000 cycle alternating current, interrupted at a- 20- cycle rate. This interrupted- 1,000 cycle current is transmitted over'toll line 220 and received at the incoming end by the receiving circuit equipment 350 and is then transmitted through the input transformer 352 to the input circuit of vacuum tube 353 where it is amplified. An anti-resonant circuit 354 connected between the plate circuit of the tube 353 and the grid or input circuit of the vacuum tube 355 makes this latter tube responsive to alternating currents whichdo not vary greatly from 1,000 cycles. Vacuum tube 355 acts as a rectifier, causing the polarized relay 356 in its output circuit to operate and release at the rate which corresponds to the rate of interruption of the 1,000 cycle current received;

i. e., the armature will vibrate in this instance at the 20 cycle rate causing the relay 357 included in the circuit controlled by this relay 356 to be operated as it is tuned to respond only to alternating currents of this frequency. The operation of relay 357 closes an obvious short-circuit at its armature and front contact to ground for the energizing circuit for relay 358, causing relay 358' to release. The release of relay 358 closes a circuit for relay 302 as follows: battcry, left hand winding of relay 302, right hand --armature and back contact of relay 303, outer right hand armature and back contact of relay 323, make-before-break contact of relay 358 to ground. Relay 302 operates in this circuit and closes a locking circuit for itself from battery, left hand make-beforebreak contacts of relay 303, right hand armature and front contact of relay 302, right hand winding of relay 302 to ground and also closes a circuit for bus signals 304 and 305 as follows: battery, left hand armature and front contact of relay 302, windings of busy. signals 304 and 305 in parallel to ground. A circuit is also closed by relay 302 from battery, left hand make-before-break contacts of relay 303, right hand armature and front contact of relay 302 through supervisory lamp 306 to ground causing this lamp to light to indicate to the operator at 310 that a connection is desired.

In answer to this signal, the operator at 310 inserts plug 311 intojack 314 and relay 303 is operated over an obvious circuit. The operation of this relay opens at its makebeforebreak contacts the locking circuit for relay 302 which .in releasing causes the supervisory s i nal 306 to be extinguished. However, the usy signals 304 and 305 are maintained operated by the closing ofthe left hand armature to the corresponding front contact and battery at relay 303. The operator at 310 now actuates her listening key connecting her telephone set in the usual manner to the cord circuit and receives the details of the call from the operator at who has also by this time actuated her listening key 32 and connected her telephone set to her cord circuit. .The operator at 310 then proceeds to extend the connection to the wanted" subscribers line and call the subscriber in accordance with the well established practice in the art of telephony. Con versation between the subscriber at 10 and the called subscriber may then take place.

In case the call extended to'the operator at 310 is intended for a subscriber that may be reached through the assistance of an operator at another distant exchange, i. e., if the operator at 310 is merely employed as a conthe ringing key 34 Whenever suc visory signals'from the operator at 100 at the originating exchange over the toll lines 220 through the incoming toll line equip ment 300 to a-co'rd circuit of the operator at 310 and this may. be done by the 0 eration of supervisory signaling is desired.- The function of the circuits in this instance'is the same as that already described when the key 34 was opcrated the first time except that when relay 358 is released as a result of thereception of an impulse of 1,000 cycle alternating current interrupted at a 20 cycle rate, the relay 340 is operated iuplace of relay 302 over a circuit as follows: battery, winding of" relay 340, righthand armature and front contact of relay 303, outer right hand armature and back contact of relay 323 to ground at the make-befor -break contacts of relay 358..

This causes the operation of relay 340 which disconnects the tip and ring leads of the toll line 220 and connects'the 20 cycle alternatingcurrent source and ground to the tip and ring leads of the switchboard end of the outgoing toll line equipment 300, to the jack 314 to a cord circuit of the operator at 310 causing supervisory indications to bedisplayed in said cord circuit at 310 as is well known in the art.

In case the incoming operator at 310- at the distant exchange decides toext-end a connection to a subscriber that may be attended to by the outgoing operator at 100, 1. e'., a

connection in the opposite directionon the toll line 220, a procedure similar to that described above is followed. The operator at Y so 310 actuates her ringing key' (not shown) in the same manner as the operator at 100 operated her ringing key 34, 20 cycle alternating current and ground are thereby connected to the tip and ring leads of the incoming toll line equipment 300 causing the relay 315 bridged across line to operate through the retardation coils 316 and condenser 317. The operation of relay 315 closes an obvious operating circuit for relay 320 and-this relay',"after having disconnected the portions of the tip and ringleads connected tothe jack 314, connects current from the 7 OOcycle alternating current source interrupted at a I 7 20 cycle rate to the tip and ring leads of the till toll line 220. This impulse of interrupted voice frequency current is transmitted, at the outgoing toll line equipment 200 through the upper and innerlqwer armatures and back contacts of relay 222 and the left hand armatures and back contacts 'of relay 218 to the receiving circuit 250, through the input transformer 252 toztheinput circuit of the vacuum tube 253 where itis am lified; The anti-resonant circuit connected 'etweenthe hshed for the ener izin cuit of a second tube 2 responds to alternating currents'which 'do not vary greatly from 700 cycles. The second tube 255 receives the 700 c cle current, acts as a rectifier and causes t e relay 256 connected in its plate circuit to operate and release at a rate which responds to the rate of interruptions of the 700 cycles received, i. e., in this instance, at a 20 cycle rate. J Relay 2 57 which i is tuned to respond only to20 cycle ,cur-

rent is include the normal make-before-break contacts of relay 258, and from battery, right hand winding of relay 217 to ground at relay 258. Relay 217, in operating, closes a locking circuit for itself from-battery, left-hand armature and back contact of relay 203, inner lefthand.armature and front contact of relay v 217 to ground through the left-hand winding of this relay. Relay 217 also closes an obvwuscircuit for relay 214 which in turn opens the circuit in which relay 212 is bridged across the line to prevent false operation of this relay. Relay 240, in operatlng, closes a locking circuit foritself from battery, left-hand armature and back contact of relay 203, left-hand armature and front contact of relay 240 to ground through the lefthand winding of this relay. The operation of relay 240 closes an obvious circuit for the busy signal 205 and also causes the illumination of lam 241 from the battery at relay 203 throng the left-hand armature and front contact of relay 240.

In answering this signal, the operator at 100 inserts plug 15 into jack 210 and relays 24, 23 and 202 are operated but lamp 25 is not lighted, as hereinbefore described. The operation of relay 202 causes the operation of relay 203. which in turn opens thelocking circuits for relays 217 and 240 thereby releasing these relays and extinguishing lamp 241 but the circult'for the busy signal 205 is maintained-from the battery supplied at the left-hand armature and front/contact of relay 203. The operator at 100 now actuates her listening key 32 connecting her telephone set in the usual manner to the cord circuit and receives the details of the call from the operator at 310 who. has also by this time actuated v.her listening key corresponding to key 32 and connected her telephone set to her cord circuit. The operator at 100 then proceeds .to. extend the connection to thewanted subscribers lineand calls the subscriber. in accordance with thewell established practice in the art of telephony. Conversation between the subscriber at the distant exehan e and the subscriber at 10 may now take p ace.

In case the call extended to the operator at 100 is intended for a subscriber that may be reached through the assistance of an operator at anothercexchange in this direction, i. e., if the operator at 100 is merely employed as a connecting operator for a through-connection, it ma be necessary to send supervisory signals rom the operator at 310 at the distant exchange over the toll line 220 through the outgoing toll line equipment 200 to the cord circuit of the operator at 100. This ma be done by the operator at 310 actuating er ringin key whenever such supervisory signaling is de'sired.- The function of the circuits inthis instance is the same as that already described whenthis ringing key was first operated except that when relay 258 is released as a result of the reception of impulses of 700 cycles alternating current interrupted at a 20 cycle rate, the relay 213 is operated in place of relay 240 over a circuit as follows: battery, winding of relay 213, left-hand armature and front contact ofrelay 202 to ground at the makebefore-break contacts of relay 258. This causes the operation of .relay 213 which disconnects the tip of ring leads of the toll line 220 and connects the 20 cycle alternatin current source and ground to'the tip an ring contacts of the jack 210 and plug 15 to the cord circuit of the operator at 100 causing supervisory indications to be displayed thereat as is well known in the art. That is relay 30 is operated causing lamp 25 to light.

These various connections may be released when the conversations cease by merely 'removing the plugs and the various relays will consequently return ,to normal positions as is well known in the manual telephone art.

. The second type of connections to be considered is a call extended on the so-called automatic basis, i. e.,from a subscriber at 10 through the toll operators position at 100 at the originating exchan e over the same toll line 220 to the incoming toll line equipment 300 which will, in this instance, be prepared to extend the call through the automatic equipment such as isshown in Fig.

4-and through the associated switches to a subscriber such as 410. As the automatic exchange equipment does not form any part of this invention, only a small portion has been shown to sufficiently illustrate how it is affected by and how it reacts upon the toll line equipments in accordance with this invention. In fact any well known type of automatic equipment may be used as long as the proper signalindications may be sent or received to perform the proper functions in response to dialing and supervisory signal operating relays 26 and 27, as hereinbefore.

described. The toll operator at 100 will in this instance, instead of operating the ringing key 34, operate the dialing key 35. The operation of this key closes an obvious circuit for relays 36 and 37 The operation of relay 36 closes an obvious circuit for relay 42 which in operating closes, at its inner right hand armature and make-beforehreak contacts, a circuit to ground for lamp 25 and opens at its outer left hand armature and make-before-break contacts, the circuit for relays 23 and 24 and extends at the outer armature and front contact the sleeve circuit to the marginal relay 152 associated with the dialing circuit. Relay 152 operates in this circuit and causes a circuit for lamp 25 to be closed as follows: battery,'left hand armature and back contact of relay 153, inner right hand armature and front contact of relay 152, lead 43, inner left hand arma ture and front contact of relay 36, lamp 25 to ground at the make-before-br'eak contacts of relay 42. However, this circuit is merely momentary and lamp 25 is not lighted or at least not lighted long enough to be noticed for reasons as hereinafter described. Relay 37 in energizing, disconnects at its upper and inner lower armature, the incoming end of the tip and ring leads of the cord circuit and extends the outgoing ends of the tip and ring leads to leads 40 and 41 respectively, which are connected to ground and battery at the armatures of relay 151 associated with the dialing circuit.

An impulse from this battery and ground is therefore now sent out over the line to the outgoing toll line equipment 200 and causes the operation ofthe relay 212, over a circuit that may be traced as follows: battery, inner left hand armature and back cont-act of relay 151, lead 41, inner lower armature and front contact of relay 37, ring contacts of plug 15 and jack 210, lower armature and back contact of relay 213', left hand armature and back contact of relay 214, one section of retardation coil 215, left hand armature and back contact of relay 216, winding of relay 212, left hand section of retardation coil 215, upper armature and back contact of relay 213, tip contacts of jack 210 and plug 15, upper armature and front contact of relay 37, lead 40, middle left hand armature and back contact of relay 151 to ground. The operation of relay 212 causes the operation of recontact of relay 218 to tion of relay 216' also y the operation of its outer right hand armature closes a lock-. ing circuit. for relay 203 as follows: battery,

lay 216 over an obvious circuit-and relay 216 closes u locking circuitfor itself through its inner right hand armature and front contact through the right hand armature and back round. The operawinding of relay 203, inner right hand armaouter right hand armature of relay 216 also ture and front contact of relay 203, outer right hand armature and front contact of ay 216to. ground. The operation of this removes the short-circuiting ground for the right hand windingof relay 202 causing the resistance in the sleeve circuit to increase sufiiciently to cause relay 152 to release and open the circuit for lamp 25 at itsinner right hand armature and front contact thereto the line at relay 151.are disconnected after a short period as'the slowto operate relay 151 operates from battery, windlng of relay 151 lower armature andifront contact of rela-v 37 to ground. The period of release is for this impulse may be traced as follows:'

determined by the slow action of relay 151. As soon as relay 151 operatesa 1,000 cycle current source interrupted at a 40 cycle rate is connected to leads 40 and 41 and an impulse therefrom is transmitted to the outgomg toll line equipment over the tolliline 220 to the incoming toll line equipment 300 to cause various operations ashereinafter de-' scribed to take place. .The complete circuit from the. source of 1,000 cycle current interruptcd at 40 through the armature's and front contacts of relay 154, inner and middle left hand armatures and front. cgntacts of relay151, leads 40'and'41, upper and inner lower armatures and front contacts of relay 37, tip and ring contacts of plug 15 and j ack 210, upper and lower arinatures and backcontacts'of relay 213, upper and lower inn-er armatures and backcontacts of relays 209 and 222, tip and ring leads of toll lines .220

' through the input transformer 352 of the re 'ceiving circuit equipment .350 which acts in;

.a'lmanner as hereinbefore described to cause the operation of relay 360 which-short; cirv cuits'the energizing circuit for relay 361' causing it torelease and connect a ground to follows: battery, winding of'relay'322, inner:

vacircuit for the energization of relay 322;

This circuit for relay 322 may be tracedas right hand armature and back contact ofre lay 323 to round at relay 361. The operation of re ay' 322 connects battery to the windingv of relay 303 causing this relay to operate as follows: battery, inner right hand armature and front contact of relay 322,.

winding of relay 303 to ground. The operation of relay 303 causes the operation of signals 304 and305 from battery supplied at the left hand armature and front contact of this relay over an obvious circuit. The OP- eration of relay 322'also closes a circuit at its left hand armature and front contact for relay-323 in series with itself but this relay does not operate until the ground at 361 has been removed in which case relay 323 operates and relay 322 and 323 are then held up over the following circuit: battery, winding of relay 322, winding of relay 323, left hand armature and front contact of relay 322, armature and back contact of relay 324 to ground. The operation of relay 322 also closes at its outer right hand armature and back contact a. circuit from ground at the make-before-break contacts of relay 362 to the automatic exchange equipment for the conditioning of this equipment for extension of a call as follows: battery to'the slow-torelease relay 406, winding of this relay, armature an d back contact of relay 407, lead 450, outer left hand armatureand back contact of relay 325, outer right hand armature and front contact of relay 322 to ground at the make-before-break contacts of relay 362.

This causes the operation of relay 406 which in turn causes the slow-to-release relay 408 to operate over an obvious circuit and this relay establishes an obvious energizing circuit for relay 411. At its inner right hand armature, relay 411 establishes a circuit for relay 407 which may be traced from battery, winding of relay 407, conductors 451 and 462 to ground over the front contact and inner righthand armature of relay 411. Relay 407 in attracting its "armature opens the original energizing circuit for relay 406 which relay thereupon releases, removing'the original ground from the} winding of relay 408 which, however, now remains operated in a circuit extending from battery through the winding ofrelay 408, armature. and front contactof relay 407 to ground over lead 450,

make-before-break contacts ofl'relay 3.62;; At

outer left handarmature and back contactof. relay 325, outerrighthand armature and front contactjof .relay322. to ground at the lays 422 andy 416: At. its outer right; hand circuit extends .;from batter through winding of magnet" 412, outer rlglitfhand arma ture and back contact of relay 416to ground;

--.armatui'e,j relay v'41'1 prepares a, circuit, causfling the start magnet 412 to operate, This at. outer right hand armature and front contact of relay. 411. Magnet 412 causesthe ro-' tary ma et 418 to operate in an obvious circuit. he rotary ma et 418 in operating causes the line switch B to start hunting for an idle district sender in a manner well known in the art.

When an idle district switch such as isdiagrammatically indicated at G is reached, the idle condition thereof being designated by the presence of battery on the test terminal thereof, relay 422 operates in a circuit extending from battery, contacts of sequence switch spring 440, armature and back contact of relay 425 terminal 420 and wiper 421 of line switch front contact and inner left hand armature of relay 411, both windings of relay 422 to ground through the winding of relay 416. Relay 422 in attracting its armature short-circuits its own right hand winding thereby reducing the resistance in the circuit just traced, sufliciently to permit marginal relay 416 to operate in series with relay 422. Relay 416 upon energizing causes cut-ofi' relay 414 to energize'in a circuit extending from battery winding of cut-ofi relay 414, front contact and armature of relay 416 to ground at the outer right hand armature and front contact of relay 411. Relay 414 in attracting its outer right hand armature opens the energizing circuit for magnet 412 whereupon this magnet restores causing the rotary magnet 418 to release. At its inner right hand armature relay 414 prepares a circuit for relay 427 for supervisory purposes which will hereinafter appear. In attracting its outer left hand armature, relay 414 locks up under the control of relay 411, and at its two inner armatures 423'and 424, closes through the tip and ring leads to corresponding terminals of switch F for purposes hereinafter to be set forth. At its in ner left hand armature, relay 414 closes an energizin circuit for relay 425 from battery, win ing of relay 425, terminal 475 and wiper 441 of line switch F to ground at this inner left hand armature and front contactof relay 414. Relay 425 in attracting its armature removes battery from the test terminal 420 of line switch F, whereupon relays 416 and 422 release, the former opening the original energizing circuit for relay 414 which, however, remains locked up as hereinbefore described.

The operation of the control relay 425 ofthe selected district switch cause an idle sender to be selected in the well known manner whereupon relay 500 operates causing relay 501 to operate through intermediary relays (not shown) to cause a dialing signal to be given to the operator at 100 in the following manner. Relay 501 in operating places a ground on the tip conductor of the line switch F. This ground causes relay 427 to operate in a circuit extending from battery through the winding of relay 427, 1nner right hand armature and back contact of rela 428, contacts 423 of relay 414, wiper 98 and contact 431 of switch F, lower left hand contacts of sequence switch spr1ng480 (1+16), upper right hand c0ntacts of said spring (2%+10) to ground at the contacts of relay 301. Relay 427 in operating causes the ground at relay 411 to be connected to lead 451 which causes the operation of relay 326 as follows: battery, winding of relay 326, lead 451, armature and nects the 700 cycle alternating current sourceinterrupted at a 40 cycle rate to the toll hne 220, the outgoing toll line equipment 200 and the cord circuit at 100 to cause the lamp 25 to become illuminative to indicate to the operator at 100 that the dialing may begin. This signal from the 700 cycle current interrupted at the 40 cycle rate is re ceived at the receiving circuit equipment 250 over the following circuit: from the 7 00 c cle source interrupted at the 40 cycle rate t rough the left hand armatures and front contacts of relay 326, upper and lower armatures and back contacts of relay 220, left hand armatures and back contacts of relay 218 through the primary winding ofinput transformer 252. This impulse is. effective through the receiving equipment 250 in the manner as hereinbefore described to cause the operation of relay 260 which in turn causes the short-circuiting of the energizing circuit for relay 261. Relay 261 in releasing applies a short-circuiting ground for the left hand winding of relay 202 and thereby causes the resistance in the sleeve circuit to be decreased. The marginal relay 152 is consequently operated as hereinbe- 5 fore described to connect battery from the left hand armature of relay 153 through the lamp 25 causing it to light as hereinbefore stated as a signal to the operator at 100 that the dialing operations may begin.

Current from the 1000 cycle source in the dialing circuit is now in position to be connected to the receiving circuit 350 as a pulsing current. When, therefore, the operator at 100 operates the dial in accordance with the number of the desired line, ground is connected to the winding of relay 158 from the off-normal contact 156 of the dial 155, causing the relay 158 to operate over an obvious circuit. The operation of relay 152. The'operationof relay 153 also at its left-hand armature and back contact removes battery from the circuit, forlamp 25 which is thereby extinguished. It should be noted that the lamp 25 remains extin- I wthel700 cycle source lnterrupted atthe 40. cycle rate'from the toll line 220 causing. re- 1 7 period due guished during the entire dialinlg p t e opera 1011 to the backing up relay 153. T

of rela 158 connects one side of the c ireuit' I from t e 1000 cycle source to'the lead 41 at its right-hand armature and back contact. The pulsing contacts 157 of the dial open for each ulse duringth'e returnmovement of the dial to normal and thereby cause the relay 159 to release over an obvious circuit and connect the other lead from the 1000 cycle source to lead 42. In this'manner.

pulses are transmitted toxthedistant end over the outgoing toll line equ1pmen't 200 and the toll line 220 into the-receiving cir cuit 350. Each pulse transmitted isequal in time to the open period of the :pulse con-; tacts 157 of the dial.. 'When,ftherefore, the 1000 cycle pulses are received over the line from the outgoing end they are transmitted through the input transformer-.352Jtorelay- 356 as hereinbefore'describedand cause-this relay to operate and release at a'rat'e corresponding to the rate of interruptions of the 1000 cycle current by the operation of relay, 159, thus disconnecting the ground at'lts" armature from leads 363 and 450 to cause selecting operations to be performed by the automatic exchange equipment shown in Fig. 4. That is relay 500is caused to respond to the impulses over a circuit as follows: batter winding of pulsing relay 500, lower rlght-hand contact of sequence switch spring 493 '(3+10 upper lefthand contact of this sequence switch spring (1+16), contact 432 and ring Wiper 445 of line switch F, contacts 424 tv relay 414',

back contact and outer right hand' armature of relay 428, armature and frontcontact of relay 407, lead 450, outer'left hand armature and back contactof-re1ay 325,iouterright hand armature and *front contact of relay 322, armature and --front contact of relay 362', conductor .363" m gro nd fat, the armature of relay 356'. Whenground' is removed from relay 356 in. accordance with the interruptionsjofith'e' dial ,cnntact, the

1 ground is also removed from the relay 408.

However, this relay remains. operated dur ing the dialing period. owing to its slow releasing characteristics; p k

To turn now to the operationof theautomatic exchange equipment I when all the pulses are registered n the sender, ground" is removed from the tip leadf'at-relay'501,

thereby causing 'relay 427 torelease which in contact, the circuit for relay 362 which thereby is released causing the dialing lead to be broken at its armature and front contact but substituting therefor the ground at its makebefore-break contact to lead 450 to maintain the sender relay 500 energlzed for the time being Relay 326 also, in releasing, removes,

lay- 261 in the receiving circuit 250 tobe-Y come energizcdto remove the short circuib:

ing ground from the right-hand Winding relay 202. This increases the resistance in the sleeve circuit and causes the marginal relay 152 to release. The release of relay 152inturn opens the locking circuit for'rela'y 153. which is also released to prepare the circuit for the subsequentlighting' of'lamp;.2 5 as I hereinafter described.

When'the wanted subscribers lineat 410 contactw429} from sequence switch contact 485 to wiper 23.8 of-the line finder switch F,

is reached a ground is connected at the,

whereuponrelay 428' is operated ina' cir-,

cuitwhich may be traced from battery,

winding of relay 428, contacts 437, contacts 439 of relay 414, wiper 438 and terminal 429, contacts 485 to ground. Relay 428 looks through its contacts 447 to ground" under control of relay 414. At its inner right-hand'armature, relay .428 disconnects relay 427 from the tip lead, and at its inner left-hand armature and front contact," connects'relay 427 to the wiper 438' of the line finder switch F to groundat- 285. At its outer left-hand armature, relay 428 establishes a circuit for relay 327 which may be traced frombattery right-hand winding of relay 327, lead 452, outer left-hand armature and front contact of relay 428, conduc-' tors 451 and'462, innerhright-hand armature and front contact of relay 411 to ground.

Relay 327 establishes a lockingcircuit for itself 'from battery through its left-hand winding and left-hand armature and front contact, armature, and back contact of relay 324 .to ground." Relay 327 also breakspermanently'at' its.right hand armature and I i back contact the circuit for re1ay-362 so that this relay. cannot be again energized upon the subsequent... energization of relay 4 326 p as" hereinafter'described. The ground. from re.'-'

lay411also' causes the operation of relay" 330 r as followsr-battery wi'ndingfof,relayj'330, onterfllower makeefor'e-breakf Contact of relay} 330 t-o'lead 452 to ground at 41 1. ,Re-f lay 330-locksup over its lower. armature and fro'nt contact through lead 4533s; itshould be notedthat this lead also received "ground; I

from the inner armature and. front gcontact of relay 411'over lead "462. 'The operation v no i U 1,606,816 gm of relay 330 performs no useful function at described 'in connection with the calls exthis time. The ground on lead 453 also tended on the 'ringdown ba'sis, except'thatithe causes the operation of relay 331 from batrelease of, the relay 358 in response to the,

tery, winding of relay 331 to ground on contransmission of a' current impulse of 1,000 ductor 453. The operation of relay 331 conc cles interrupted at the cycle rate causes nects the 1000 cycle source, interrupted at a t e operation of relay 499 in the automatic 40 cycle rate, to the armatures of relay 332 eq'ui ment over a circuit as follows: battery, causing a short impulse to be sent out on the Win ing of relay 499, sequence switch con-.

I tip and ring leads but this impulse is not tacts 494, terminal 496, wiper' 497, right hand used on this type of connection and is there armature and front contact of relay 471, fore of no significance.- The use in'another lead 454, outer. right hand armatureand type of connectionwill be described later. front contact of relay 323 to ground at the Relay 332 which is slow to release determines make-before-break contact ofrela 358. The i the length of this impulse and is released by operation of relay 499 causes t, e applicathe operation of the lower armature and. tion of ringing current from the source 492 back contact of relay 331. v over the established connection to actuate If the wanted subscribers line is idle, the the wanted subscribers bell.

ground connected at 429 now due to the When the called subscriber answers in reoperation of relay 428 causes the operation sponse to the ringing si nal by removinghis of'relay 427 over the following circuit: batreceiver from the switc hook, ground is retery, winding of relay 427, inner left-hand moved from the contact 485 at the switch F,

'-again-causes the release ofrelay 261 which armature and front contact ofrelay 428, thereby opening the circuit for relay 427. contacts 239 of relay 414 wiper 438 contact Relay 427 in releasing, opens the circuit for 439 to ground at 285. The energization of vrelay 326 causingulamp 25 at the operators relay 427 again connects lead 451 to position at 100 to be extinguished by the re- Relay 326, in operating, again connects the fore described to indicate to the operator 1000 cycle current source, interrupted at'the that the subscriber has answered. Conver- 40 cycle rate, to the toll line 220. The resation may now begin between the subscriber ceiving circuit corresponding to this impulse at 10 and-the subscriber at 410.

At the termination of the conversation, applies a short-circuiting ground to the the subscriber-M410 upon replacing the reright-hand winding of relay 202. It should ceiver on the switchhook again causes be remembered that relay 153 is at this time ground'to be placed on the terminal 429 of released so that when'relay 152 now reswitch F from contact 485, thereby causing sponds, due'to the decrease in resistance of the energization of relay 427. Relay .427,

the sleeve a circuit for lamp 325 is comin operating, causes ground from relay 411 pleted from battery at relay 153, andv this to be connected to lead 451 causing the relamp is therefore lighted to indicate to the energization-of relay 326 and the consequent operator at 100 that the called subscriber is application of current to the toll line from idle and that ringing operations may begin. the 700 cycle source interrupted at the 40 When therefore all the digits correspond cycle rate. This, in turn, as hereinbefore ing to the number of the desired line have described, causes the lighting of lamp 25 been dialed, the operator at 100 may reby the energization of relay 23. store the dialing key 35 and thereby release The illumination of lam 25 at this time relays 36 and 37- but leaves relay '42- enerserves as a disconnect signa to the operator gized for the time being. Therelease of reat 100 and she proceeds to take down the lay 37 disconnects the dialing circuit 150 connection by withdrawingplug 15 from from the operators cord circuit. The re jack 210. As a result of this'action, relays lease of relay 36 causes the release ofrelay 24, 23 and 202 are immediately released. 152 and also breaks the energizing circuit for The release of relay 24 causes the release relay 42, but this relay, being slow in reof relay 42 and the extinguishing of lamp leasing, is provided with a holding circuit. 25. The release of relay 202 causes a short 7 from the armature and front contact of resignal from the 1000 cycle source, interlay 24 which operates in series with marrupted at the 40 cycle rate, to be sent to the ginal relay 23 over the sleeve circuit as soon incoming toll line equipment 300 as follows, as relay 36- is deenergized' and lamp 25 is, i. e., a circuitis closed for relay 224 from therefore, maintained energized as it receives battery, winding of relay 224, outer rightbatteryfroni the armature and front contact hand armature and front contact of relay of relay 23. 203, right-hand armature and back contact As the operator at 100 is now connected of relay 202 to ground. The operation of ground causing the operation of relay 326. lease of the marginal relay 23 as hereinbe- 4 thrpugh the automatic equipment, to the relay 224 causes current from the 1000 cycle Wanted subscribers line, she may signal the source, interrupted at the 40 cycle rate, to subscriber by the operation of key 34 and be connected to the left-hand armatures and the circuits function in the same manner as back contacts of relay 218 to the toll line and through'the receiving equipment 350 to cause the release of relay 361.. The -release of relay 361 thereby closes acircuitfor 0 ens the obvious energizing circuit for the s ow-to-release rela 225 which in releasing closes an obvious circuit for the slow-to-release relay 218 which, in attracting its armatures, breaks the connection from the 1000 cycle source to the toll line at its left-hand armatures and back contacts. The duration of the impulse is therefore determined by the operating characteristics of relays 225 and 218. The operation of relay 218 also opens atv its right-hand armature and back contact, the locking circuit for relay 216 which, upon releasing, opens the locking circuit for relay 203; The release of relay 203 opens the energizing circuit for relay 224 which, in releasing, disconnects the 1000 cycle source and causes the energization of relay 225 which in turn releases relay 218. When the impulse, therefore, ceases relay 324'is energized in series with relay 335 from battery, through the winding of relay 335, winding of relay 324, left-hand armature and front contact of relay 335, left-hand armature and front contact of relay 323 to ground. The operation oi relay 324 opens the locking circuit for. relays 323, 322 and 327 which relays all release. The release ofrela 322 opens the circuit for relay 303 which, in releasin disconnects the busy signals 304 and 305.

elay 322, also opens at its outer righthand armature and front contact the lead 450 to round for relay 408 which, after an interva releases and opens the energizing circuit for relay 411. Relay 411, in retracting its outer left-hand armature, opens the locking circuit for relay 414 which relay thereupon releases. At its inner right-hand armature, relay 411 disconnects round from the windings of relays 407 an 471 whereupon'these rela s release. Relay. 471, in releasing, opens-t e normal. energizin circuit for relay 499. The restoration of t e automatic equipment now takes place in the manner well known in the art.

If, in-the course of completion-of the connection by the automatic exchange ;equip-. ,me'nt all trunks for extending the connec tionare found busy, intermittent ground isv connected to the terminal 429, from an interrupter such as 483 or an other suitable means, at a certain rate, or example, 60

interruptions per minute. The first impulse to ground will operate relay 428-and the following ground operate relay 427 which thereafter willbe interrupted at the corresponding rate to alternately close and open the circuit for relay; :This j relayfwill consequently alternately co'n'rueict and disconnect the source-of 700 cycles interrupted at a '40 cycle rate to" the toll line 220;;and the lamp 25 willtherefore beintermittently lighted at 60 interruptions per .minuteflinja manner which is believed tol'beobviou'si The flashing of this lamp indicates: to the] operator that all trunks arebu'sy.

In the same manner if'the called sub- Y scriber is. found busy, ground will be connected to the terminal 429 at a difierent rate, such as will produce, for example,

120 impulses per minute from an interrupter such as 484 and the flashing of the lamp at this rate will indicate to the operator that the wanted subscribers line is busy.

It should also be noted that lamp 25 may be flashed by the called subscriber at the rate at which his switchhook is moved up and down during the talking period. Relay 326 is operated when the switchhook is down and released when the switchhook is up. I

If the operator at desires to rering the called subscriber after he has replaced his .receiver on the switchhook, she operates the ringing key 34 and the circuits function in exactly the same manner as when the wanted subscriber was'first called'that is relay 358v is released by the transmission from the source 492 through the established connection to scriber. I I

In case an automatic call extended from resignal the wanted subthe automatic equipment is not intended :tor

a subscriber, such as the one connected at 410, but for a subscriber that may be reached through the mediumof another toll line,

i. e. if aterminal bank, for example, the

one represented by terminals 510-, is reached 4 by thebrushes of the switch 511 and ,these to another distantexchange and a subscriber terminals are connected to a toll lineleading us I automatic equipment at Fig. '4 will then merely serve for a: so-called through con [I nection. .Th'e equipmentsf ass'ociated with .this second toll line may beidentical with that shown in Figs. '2 and 3 which may also serve for a through connection'andv would in that case be reached from a sWitch'such as 275 making contact of this toll line.

second automatic exchange. The first iunc-,

, The operator at 100'wi1l, thec' s a through"connection not-only dial aj num-' her that will bring the connection up to with terminals v276 laction after the connection has been extended to terminals 510 in response to the first numbcr, will then be the transmission over the second toll line for a short period of current from the 1000 cycle alternating current' source interrupted at a 40 cycle rate as has hcreinbefore been described at the operation of relay 331. This short application of current conditions the second distant exchange for receiving impulses fromi theop-- erator at representing the second number and it can be seen that as previously described when relay 332 operated the talking leads 455 and 456 will be extended to the toll line 220 at the upper and lower make-before-break contacts of relay 322. Leads 455 and 456 are then also, of course, connected over the second toll line to a second distant exchange upon receipt of a signal indication from the distant toll line equipment to indicate that the second number may be sentin the same manner as hereinbefore described in connection with the extension of a call to an automatic subscriber through the equipment at 300 and Fig. 4. The operator at 100 may now therefore, proceed in dialing the second number and the procedure will be the same as has already been described in connection with the extension of a call to the subscriber at 410. It should be stated that a relay similar to relay 222 is operated to disconnect the corresponding outgoing toll line equipment such as that shown at 200 from the second toll line. No further description need to be made as the following functions are exactly the same at the second distant' a manner similar to the operator at 310 only that this operator is reached by having the operator at 100 dial a certain number or special code. In this case the operator at 100 proceeds in the same manner as when dialing for an automatic subscriber such as the one located at 410 only instead of reaching subscribers line terminals she will be connected to terminals such as 515, connected directly'to a ground and battery. This battery and ground is transmitted back over the line and will cause the operation of' relay 516. Relay 516 in operating causes ground to be connected to lead457 resulting in the o eration of relays 325 and 341 over the folowing circuit: battery, left-hand winding of relay 325, lead 457 to ground at relay 516 for the energization of'relaying of this relay and its right-hand armature and front contact to ground at the outer left-hand armature and back contact of re- .lay 342. This relay. 341 at its left-hand armature and front contact closes an obvious circuit for the signal 343 which is thereby operated and indicates to the outdelayed operator that a connection is de-.

sired by-the line associated with jack 344. Relay 325 rovides a locking circuit for itself from attery, through its right-hand winding and inner right-hand armature and front contact to ground at the armature and back contact of relay 324. This relay 325 also prepares a locking circuit for relay 345, the urpose of which will be hereinafter descri ed and at its outer left-hand armature and .back contact removes the ground connection at relay 362 for lead 450 which causes the automatic equipment in Fig. 4 to be released to normal as hereinbefore described. When the out-delayed operator in answer to the lighting of lamp 343 inserts the plug of her cord circuit into jack 344, relay 342 is operated in the well known manner and the operation of this relay opens the locking circuit for relay 341 which is thereby released and causes the lamp 343 tobe extinguished; Relay 342 in operating also closes an obvious circuit for relay 345 which now operates and locks to the ground at relay 324 over its inner left-hand arma- 1 ture and front contact and outer right-hand armature and back contact of relay 325.

Relay 342 also disconnects the tip and ring leads to jack 314 from the line, whereas relay 345 causes the operationof relay 303 over an obvious circuit. The operation of relay 303 causes the operation'of busy signals 304 and 305 as hereinbefore described. The connection between the operator at 100 and the out-delayed operator is now completedand conversation may take place,

It should be noted that in the event the .out-delayed operator is used in throughvconnection the operator at 100 may send supervlsory signals to this operators cord circuit by virtue of the operation of relay 303 or through the connection completed at the inner left-hand armature and front contact of relay 325 by operations as hereinbefore described that will result in the release of relay 358, that is, relay 340 will be operated over a circuit as follows: battery, winding of relay 340', inner left-hand arma-' ture and front contact of relay 325, outer ri ht-hand armature and-front contact of.

re ay 323tofground at. relay358 or from battery at relay 340 through the right-hand armature and front contact of relay 330 to ound at relay 358. The operation of reay 340 as hereinbefore described, connected currentfrom the 20 cycle source and round to the tip and. ring leads connected t rough jack 344 to cause the supervisory lam 1n the operators cordcircuit at 311 to 11 In case the out-delayed operator eslres to-recall the operator at 100 she may do so by movin her plug in and out of jack 344, thus causlng the momentary release of relay 342 which will then complete a circuit for relay 326 from battery, winding of relay 326, left-hand armature and front contact of relay 345, inner left-hand armature and back contact of relay 342 to ground. The

operation of relay 326 will then, as hereinbefore described, connect current from the 700 cycle source, interrupted at the 40 cycle rate and cause the flashing'of lamp at 100. If the out-delayed operator desires to break the connection she removes her plug from jack 344. This causes lamp 25 to be maintained lighted to serve as a designation for the operator at 100 to disconnect which she proceeds to do as hereinbefore described.

What is claimed is:

' 1. In atelephone system the combination of a toll line with means at one end thereof for transmitting over said toll line impulses of a high frequency alternating current at certain intervals, signaling means at the opposite end of said toll line responsive only to said alternating current impulses received at said intervals, means at the opposite end for transmitting over said toll line impulses of a high frequency alternating current; of another frequency at certainintervals, and si aling means at the originating end of said toll line responsive only to said other alternating current impulses received at said intervals. a v

2. In a telephone system the-combination of a toll line with means at-one end thereof for transmitting over said toll line impulses of a high frequency alternating current applied at certain intervals and operative in response to the reception at said means of an impulse of low frequency alternating current, signalling means at the op osite end of .said toll line responsive to sal alternating current impulses, means at the opposite end for transmitting over said toll line impulses of a high frequency alternating cur-' rent of another frequency applied at certain intervals and operative in response to the reception at said means of an impulse of low frequency alternating current, and signaling means at the originating end responsive to said other alternating currents.

3. In a'signaling system, a source of high frequency alternating current of constant "high frequency alternating currents applied amplitude, a transmission line, independent means for producing and applying to said line undamped impulses of alternating current from said source periodically at one rate, a second independent means for producingand apply'ingto said line undamped impulses of alternating current from said source periodically at another rate, and means connected to said line selectively responsive to said undamped current impulses rates.

of a toll line with means for transmitting ternating currents applied at a different rate to said toll line, and means for controlling the switches in accordance with said high frequency alternating current impulses applied at said secondrate.

5. In a telephone system the combination of a tollline with a dialing circuit, means for associating said dialing circuit with any one of said toll lines, means in said dialing circuit for transmitting over a toll line connected therewith high frequency alternating currents applied at a certain rate for a short period when said toll line is associated with the dialing circuit, automatic switches at the opposite end of said toll line, means associated with the opposite end of the toll line actuated by said momentarily applied alternating currents for associating said switches with said toll line, means in said dialing circuit for thereafter transmitting dialing impulses over the toll linesaid dialing impulses consisting of high frequency alternatmg currents, and meansfor controlling the switches in accordance 1 with said dialing impu ses.

'6. In a telephone system the combinationof a toll line with a cord circuit, a dialing circuit adapted to be connected to the cord circuit, a signal in said cord circuit operated -When the dialing circuit is connected to the cord circuit, means in said dialing for connecting a momentary impulse of battery and ground to the toll line when the dialing cirwhen'periodically applied at said different g 4'. In a'telephone system the combination f switches with said toll line, and means in said dialing circuit for thereafter transmitting high frequency alternating currents applied at dialing rate for controlling. said switches in accordance therewith.

7. In a telephone system, the combination of a toll line, a cord circuit, a busy signal associated with the toll line, a signal associated with the cord'circuit, means for operatingthe busy signal when the cord circuit is connected to the toll line, a dialin circuit adapted to be connected .to the cor circuit, means for operating the cord circuit signal when the dialing circuit is connected to the cord circuit, means associated with the dialing circuit for applyin a momentary direct current impulse to t e cord circuit for transmission over the toll line, means associated with the dialing circuit for applying, after the said momentary impulse, high frequency alternating current periodically at one rate for a short interval,

means associated with the dialing circuit for thereafter applying hi h frequency alternating current periodica ly at a different rate, means associated with the cord circuit and toll line and actuated by the applied momentary impulse for disabling the cord circuit signal, and means connected to the toll line selectively responsive to the high fre uency alternating current when periodica y applied at the said different rates.

8. In a telephone system, a source of high frequency alternating current, a transmission line, means for ap lying alternating current to said line perio ically at one rate, means for applying said alternatin current to said lineperiodically at a difierent rate, automatic switching mechanism, a finder switch associated with said line, means for operating said finder switch to connect the hue to the automatic switching mechanism responsive to said current applied at the first mentioned rate, and means for controlling said automatic switching mechanism in. response to said current applied at the second mentioned rate.

9. In a telephone system, ,a source of high frequency alternating current,'a transmission line, means for applying alternating current to said line periodically at one rate, means for applyin said alternating current to said line perio ically at a dilierent rate, automatic switching mechanism, a finder switch associated with said line, means for operating said finder switch to connect the line to the automatic switching mechanism responsive to said current aplied at the first mentioned rate, and means -or controlling said automatic switching mechanism in response to said current applied at the second mentioned rate, and means for sending a signal for the release of said automatic switchin mechanism and the finder switch actuated y the second operation of the means for applying said current periodically at the first mentioned rate.

10. In a telephone system, a source of high frequency alternating current, a transmission ine; means for applying said ourrent to said .line periodicallyat one rate, an

impulse sender, means for applying said current to said line in with the operation of t e sender, subscribers lines, automatic switchin mechanism having access to said subscri ers lines, a finder switch associated with said transmission line, means for operating said finder switch to connect the transmission line with the automatic switching mechanism responsive to said current applied at the first mentioned rate, a signaling means, a second source of hi h frequency alternatin curulses in accordance rent of a di erent frequency, means or aping the operation of the impulse sender,

means for removin the applied second mentioned current groin the transmission line when all impulses from the sender have been received to prepare for the operation of the signal, means for again operating the signal by the application of said second mentioned current to the transmission line if the wanted subscribers line is idle, means for disabling the signal when the subscriber answers in response to a second removal of the second mentioned current from the transmission line, and means for again 0 crating the signal as a release when the su scriber hangs up in response to the application of the second mentioned current ,a

third time to the transmission line.

11. In a telephone system, a source of high frequency alternatin current a toll line terminating in means %or extending the line both automatically and manually, means for applying said alternating current to said hne periodically at one rate, means for applying said alternating current periodically at a difierent rate, a busy signal associated with the manual extension means, and means responsive to current ap plied at the second mentioned rate to actuate said automatic extension means to' disconnect the manual extension means from said line and actuate the busy signal thereat.

12. In a telephone system, a source of high frequency alternating current, a toll line terminating in means for extending the linerates to disassociate said manual extension 1 means to actuate the busy signal thereat and to prepare the automatic extension means for the reception of current applied at the sec- 0nd mentioned rate, and means responsive to current ap lied at said second mentioned rate to exten saidline automatically.

13. In a telephone system, a source of high frequency alternating current, a toll line terminating in means for extending the line both automatically and manually, means for applying said current to said line periodically at one rate at a second rate and at a third rate, signals associated with the manual extension means, means responsive when said. current is supplied at the first rate to operate said signals and when said current is applied at said second and third rates to actuate said automatic extension means, disconnect the manual extension means and to actuate some of said signals.

14;. In a signaling system, a source of high frequency alternating current, a transm ssion line terminating in means for extending the line both automatically and manual- 1 means for applying said current to said line periodically at one rate at a second rate and at a third rate, signals associated with said line at the manual extension means, means connected with said line responsive to said current when applied at one rate to operate said signals for the extension of the line manually, means connected to said line selectively responsive to said current when applied at said second and third rates to extend the line automatically and responsive to said current when applied at said second rate to disconnect the manual extension means and operate certain of said signals thereat.

15. In a signaling system, a transmission line terminating at one end in means for extending the line manually and at the opposite end in means for extending the line both automatically and manually, a source of high frequency alternating current of one frequency at one end of said line, a source of high frequency alternating current of anthree different rates, and means for applying current from the other of said sources periodically to the line at'two difl'erent'rates, and means responsive when the current of the first frequency applied at two of said three rates is applied 1n one direction to prepare and selectlvely extend the line autonating current, automatic switchin uency 1s 'applied in the same direction at t e other of said three rates to prepare the line for extension manually, means responsive when the current of the other fre uency is applied at one of said two rates 1n the other direction to prepare the line for extension manually and when the same current is applied at the other of said two rates in the same direction to causeisupervisory signals to be transmitted'over the manual ex-i tension. I v

16. In a telephone system, a source of high frequency alternating current, a transmission line, means for a plying said current to said lineat two di erent rates, automatically and whengeurrent of the same'fre- I matic switching mechanism, a second transtioned transmission line to'said second men-. t1oned transmission line, asecond source of high frequency alternatlng current, a second automatic switchin mechanism, means for applying current rom said second source periodically at one rate over the second transmission line through the extension pre pared by the first mentioned automatic switching mechanism, and'means at the distant end of said second transmission line responsive to said current applied fromsaid second source and to current from said first mentioned source applied at one of said rates for the control of said second automatic switching mechanism to connection beyond.

17. In a signaling system, a transmission line terminatlng at one end in means for extending the line both automatically and manually, a source of high frequency alternating current, automatic switching mechanism, a station, means for ap lying current from said source at two diil erent rates to control said automatic switching mechanism to extend a connection automatically to said station, a signal associated with the manual extension means, means actuated when said station is reached for releasing said automatic switching 'mechanism and actuating said signal at the manual extension means. 7

-l8. In a signaling system, avtransmission line terminating at one end in means for extending the line both automatically and manually, a source of high frequency altermechanism, a station, means for applying current from said source at two different rates to control said automatic switching mechanism to extend a connection to said station, a signal at the opposite end of said transmission line, signals associated with the manual extension means, means actuated when saidtstation is reached for releasing I extend the said automatic switching mechanism and actuating the signals at the manual extension means, means for seizing said manual extension means and actuating said means to disable one of the signals associated therewith, a second source of high frequency alternating current, means for applying curactuated when said manual extension means is released from the seizing means therefor, and means for actuating the signal at the opposite end ofthe transmission line when said second current-is applied to the transmission line.

In witness whereof, I hereunto subscribe my name this 19th day of June A.' D., 1924. rent from said second source at a certaln rate PAUL B.YMURPHY. 

